<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

    <button>获取验证码</button>

    <script>

        var oBtn = document.querySelector('button');

        var obj = {
            say: function () {
                console.log(this);
            }
        }

        oBtn.onclick = function () {
            this.disabled = true;
            this.innerHTML = '10';
            // setInterval(function () {
            //     console.log(this);
            //     this.innerHTML--;

            // }, 500)
            // obj.say()
            ff()

            function ff() {
                console.log(this);
            }
        }

    </script>

</body>

</html>